Engine-starter



W. L. McGRATH.

ENGINE STARTER.

APPLICATION FILED MAR.27.1919.

Patented Feb. 17, 1920.

WILLIAM L. McGRATH, OF ELMIRA, NEW

COMPANY, OF ELMIRA, NEW YOR YORK, ASSIGNOR TOECLIPSE MACHINE K, ACORPORATION OF NEW YORK.

ENGINE-STARTER.

Specification of Letters Patent.

Patented Feb. 17, 1920.

3 Application filed March 27, 1919. Serial No. 285,569.

To all whom it may concern:

Be it known that I, WILLIAM L. MCGRATH, a citizen of the United States,residing at Elmira, Chemung county, New York, have invented certain newand useful Improvements in Engine-Starters, of which the following is aspecification.

My lnvention relates to a starter for an engine such as an internalcombustion engine and pertains to the drive or transmission thereof forautomatically connecting the starting motor or other power with themember of the engine to be started and for transmitting the powerthereto. The object of my invention is to provide a novel, eiiicient.and reliable construction of drive embodying certain novel featureswith regard to both construction and resulting mode of operation.

My drive is of the -general type known. as the Eclipse-Bendix type ofdrive which is characterized by the employment of a rotatable membersuch as a screw shaft driven by a motor or other power and by a drivingmember mounted on such shaft for longitudinal movement thereof androtary move ment therewith, which driving member is adapted to eitherdirectly or indirectly engage the engine member. In the present instancethis driving member is the pinion itself and is itself the part whichdirectly engages the engine member.

The object of my invention is to produce a drive of this general type inwhich the driving member is capable. of a longitudinal movement on therotatable member or shaft independent of the longitudinal movement whichis enforced by the rotation of the shaft for advancing the pinion intomesh wit-h the engine'member. This independent longitudinal movement isa movement in direction op osite that of the said enforced longitudinmovement and takes place in the event that the pinion teeth shouldstrike the fly wheel teeth when such teeth are not in proper register,with the result that the proper cushioning action is provided with aminimum weight of parts moving for that purpose, that is to say,according to this construction, only the light pinion moves and not theentire structure including also the screw shaft and associated parts.Speaking in general terms, this result is accomplished by having thescrew threads of the shaft and pinion so construct the drive is of theBefore describing the present embodi-.

ment in detail it will be understood that the drive'may beeitherdirect-driven, as shown, or indirect-driven and also that the drivingmember may be the pinion itself, as shown, or may be merely the drivingor control member of a. separate pinion which itself directly engagesthe engine member, the broad idea of my invention remaining the same ineach case.

As shown the starting motor indicated at A has an extended armatureshaft 1 on which is mounted a rotatable shaft 2 which is here in theform of a screw shaft and which is connected to the armature or drivingshaft 1 preferably by the coiled driving spring 3. This spring isconnected at opposite ends to a driving head or collar 4 on the shaft 1and to the driving head 5 of the screw shaft, through the medium of thestuds or bolts 6 and 7 respectively.

The driving member which is here in the form of a pinion 8 isscrew-threaded upon the screw-threaded portion of the shaft 2 and isadapted to be advanced automatically into mesh with the teeth of the flywheel 9 whenever the screw shaft is rotated and until it contacts thestop nut 10 whereupon such pinion partakes of the rotation of its shaftand rotates and starts the engine. The pinion is automatically demeshedin the well known manner when the engine starts on its own power.

Now referring to the novel construction of the shaft and pinion whichconstitutes the subject matter of this invention, the screw threads 2are made very coarse, that is with an extremely wide groove orseparation between the threads as clearly shown in Fig. 1.

. pinion are made of much narrower section than the grooves of theshaft, according to the illustrated construction, the threads 8 beingonly about one-half of the width of the grooves of the screw shaft.

By the provision of screw threads on the shaft and pinion which thus fitloosely, the pinion is permitted a longitudinal backward movement to theleft of the screw shaft, which movement is not only independent of itssaid enforced longitudinal movement but is in an opposite direction.This longitudinal backward movement of the pinion'is a yielding onebyreason of the provision of a light spring 11 interposed between the lefthand end of the pinion and an annular spring retainer 12 which is heldagainst the shoulder 5 at the junction between the driving head 5 of theshaft and the screw-threaded portion thereof. This spring tends to holdthe forward side of the pinion threads against the rearward sides of theshaft threads but readily yields when the pinion abuts the fly wheel incase of improper meshing. Thus the cushioning action between the drivingmember or pinion and the fly wheel is provided for with a movement ofonl one light part instead. of a movement 0 practically the entiredrive.

In addition, the described construction permits of a rotary movementindependent of the screw shaft, which movement is advantageous inasmuchas it facilitates the meshing of the pinion and fly wheel teeth wheneversuch teeth abut. end to end. In this event, the pinion not only yieldslongitudinally, as ex lained but also rotates slightly but suflicientlyto bring itself into proper register with the fly wheel teeth.

I dinally of the rotatable member, and such- I claim:-

1. An engine starter drive including a rotatable member and a drivingmember mounted directly thereon for longitudinal movement thereof androtary movement therewith, said rotatable member having means which,when such latter member is rotated, moves'the driving memberlongitudinally of the rotatable member and such driving member beingmounted thereon for longitudinal movement relative to such ro- 'tatablemember and its said means and independent of such enforced movement bythe rotatable member.

2. An engine starter drive includin a rotatable member and a driving memer mounted directly thereon for longitudinal movement thereof and rotarymovement therewith, said rotatable member having means which, when suchlatter member is rotated, moves the driving member longitudriving memberhaving a yielding movement longitudinal of the rotatable memher and itssaid means and independent of its said enforced movement by therotatable member.

3. An engine starter drive including a rotatable member having screwthreads, a screw member screw-threaded thereon, the threads of therotatable member being separateda distance considerabl in-excess of thewidth of the threads of t e screw member, to permit of longitudinalmovement of the latter.-

An engine starter drive including a rotatable member having screwthreads, a screw member screw-threaded thereon, the threads of therotatable member being separated a distance considerably in excess ofthe width of the threads of the screw member, to permit of longitudinalmovement of the latter, and means for yieldingly holding the threads ofthe two members in contact.

An engine starter drive including a rotatable member having screwthreads, a screw member screw-threaded thereon, the threads of therotatable member being separated a distance considerably in excess ofthe width of the threads of the screw memher, to permit of longitudinalmovement of the latter, and a spring bearing against the screw .memberfor yieldingly holding the threads of the two members in contact.

6. An engine starter drive including a rotatable member having screwthreads, a. screw member screw-threaded thereon, the threads of therotatable member being separated a distance considerably in excess ofthe width of the threads of the screw'memher, to permit of longitudinalmovement of the latter, and a spring interposed between a part of therotatable member and the screw member for yieldinglv holding the threadsof the two members in contact.

7. An engine starter including a rotatable screw'shaft, a pinionscrew-threaded thereon, the threads of the shaft beingv separated adistance considerably in excess of the threads of the pinion, to permitof longitudina-l movement of the latter.

8. An engine starter drive includin a. rotatable member and a drivingmem r mounted thereon for longitudinal movement thereof and rotarymovement therewith, said rotatable member having means which, when suchlatter member is rotated, moves the driving member longitudinally of therotatable member, and such driving member being mounted thereon forlongitudinal movement relative thereto and independent of suchenforcedmovement by the rotatable member, and also for rotary movementindependent of the shaft.

9. An engine starter drive including a rotatable member having screwthreads, a screw member screw threaded thereon, the threads of suchmembels cooperating to member on the rotatable member independent of itslongitudinal movement enforced by the screw action of such rotatablemember. and also to permit rotary movement of m-h screw memberindependent of the rotation of the rotatable member.

10. .\n engine starter drive including a screw shaft. a screw memberscrmv-thremled thereon, the threads of the shaft being separated adistance considerably in excess of the width of the threads of the screwmember. and the screw member having a longitudinal movement on the shaftin a direction opposite its longitudinal movement as enforced b the.shaft, and also having a rotary movement on such shaft independent ofthe latter.

WILLIAM L. MCGRATII.

